I decided to add a small fan (Old K6 CPU fan) to my video card (Geforce 5200), it only had a heatsink and I was considering some overclocking. Anyways everything looked fine until hours later when I was installing a benchmarking program that windows crashed. After that it was a mess the video card looked horrible and glitchy outside the post and there was messages about some corrupt file, It wasnt until after I reinstalled windows that I remembered that I added the fan and unplugged it from the PSU and everything ran fine. Anyways it is still attached, what did I do wrong and is there a way that I can still use this fan?

Right now I am almost 100% sure this the fan is causing electromagnetic interference with the GPU, Does anyone know how to reduce the EMI or know what else it could be?

just get a pci slot exhaust fan like this one and mount in right below your video card

Ya im planing on purchasing one of those, today I played with this fan mod im doing and managed to get it going with no problems so far it could have just been that the card wasnt seated too firmly, I know agp cards can be very picky about that. Thanks for the reply.

i believe heatsinks are good interference shields

i don't think the fan you just installed caused the malfunction of your system. It must be the software that you installed that bugged down your windows since a videocard only performs outputs and some software controlled input through DVI..but crashing down a PC software like your OS must be blamed to the CPU-Mboard-bus-HDD and vice versa (the video card is way out of blame).
And I've been to putting several fans on video cards and got no trouble. Heatsinks are good shields to protect the processors (GPU or CPU) from the Electromagnets generated by the fan.
I hope this could help! Take care!